Inflammation is a hallmark of a variety of important human diseases, such as atherosclerosis (Libby et al., “Inflammation and Atherosclerosis,” Circulation 105:1135-43 (2002); Libby, “Inflammation in Atherosclerosis,” Nature 420:868-74 (2002)), lung inflammatory disease (Tetley, “Inflammatory Cells and Chronic Obstructive Pulmonary Disease,” Curr Drug Targets Inflamm Allergy 4:607-18 (2005)), and arthritis (Okamoto, “NF-κB and Rheumatic Diseases,” Endocr Metab Immune Disord Drug Targets 6:359-72 (2006)), etc. Over the past decades, steroids have been used as the main therapeutic anti-inflammatory agent. However, while steroids indeed exhibit a potent anti-inflammatory effect, the extensive usage of steroids also results in significant detrimental effects in patients. Thus, there is an urgent need for development of novel anti-inflammatory agents.
The nuclear-factor κB (NF-κB) is a key transcriptional factor involved in regulating expression of pro-inflammatory mediators including cytokines, chemokines, and adhesion molecules (Kunsch et al., “Oxidative Stress as a Regulator of Gene Expression in the Vasculature,” Circ Res 85:753-66 (1999)), thereby playing a critical role in mediating inflammatory responses. NF-κB is a dimeric transcription factor consisting of homo- or heterodimers of Rel-related proteins (Ghosh et al., “NF-κB and Rel Proteins: Evolutionarily Conserved Mediators of Immune Responses,” Annu Rev Immunol 16:225-60 (1998)). In the inactive state, NF-κB resides in the cytoplasm, forms a multi-protein complex with an inhibitory subunit, IκBα. Upon activation by external stimuli, the inflammatory signals converge on a set of IκB kinases known as the IKK complex. The IKK complex phosphorylates two conserved N-terminal serine residues of IκBα, leading to its ubiquitination and degradation by the proteasome. The liberated NF-κB then enters the nucleus, interacts with κB elements in the promoter region of a variety of inflammatory response genes, and activates their transcription (Liu et al., “Nuclear Factor-κB Decoy: Infiltrating the Heart of the Matter in Inflammatory Heart Disease,” Circ Res 89:850-2 (2001)). Thus, phosphorylation of IκBα appears to be the central point where diverse stimuli converge to regulate NF-κB.
Two IKKs, IKKα (IKK1) and IKKβ (IKK2), have been identified and shown to be part of the multi-protein IKK complex (Mercurio et al.; “IKK-1 and IKK-2: Cytokine-activated IκB Kinases Essential for NF-κB Activation,” Science 278:860-6 (1997); Zandi et al., “The IκB Kinase Complex (IKK) Contains Two Kinase Subunits, IKKα and IKKβ, Necessary for IκB Phosphorylation and NF-κB Activation,” Cell 91:243-52 (1997)). Both IKKα and IKKβ are Ser/Thr kinases, and each of them directly phosphorylates IκB proteins (Zandi et al., “Direct Phosphorylation of IκB by IKKα and IKKβ: Discrimination Between Free and NF-κB-bound Substrate,” Science 281:1360-3 (1998); Lee et al., “MEKK1 Activates both IκB Kinase alpha and IκB Kinase beta,” Proc Natl Acad Sci USA 95:9319-24 (1998)). Several other molecules in the IKK complex have also been identified, such as signal-regulated kinase (ERK) kinase 1 (MEKK1), NF-κB-inducing kinase (NIK), NF-κB essential modulator NEMO/IKKAP1/IKKγ, and IKK complex associated protein (Lee et al., “MEKK1 Activates both IκB Kinase alpha and IκB Kinase beta,” Proc Natl Acad Sci USA 95:9319-24 (1998); Yamaoka et al., “Complementation Cloning of NEMO, a Component of the IκB Kinase Complex Essential for NF-κB Activation,” Cell 93:1231-40 (1998); Rothwarf et al., “IKK-gamma is an Essential Regulatory Subunit of the IκB Kinase Complex,” Nature 395:297-300 (1998); Mercurio et al., “IκB kinase (IKK)-associated Protein 1, a Common Component of the Heterogeneous IKK Complex,” Mol Cell Biol 19:1526-38 (1999)). These molecules have been shown to be essential for transmitting upstream signals to IKKα and IKKβ by acting as a kinase, regulatory protein, or scaffold protein. Thus, it would be desirable to identify which of these targets can be used to modulate inflammation, and particularly agents that can be used for therapeutic modulation of these targets to treat or prevent inflammatory conditions.
The present invention is directed to overcoming these and other deficiencies in the art.